Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Color
SLA_BANJ_COLOR
Parameter: Algorithm
SLA_BANJ_ALGORITHM
Parameter: Illumination
SLA_BANJ_ILLIMINATION
Parameter: Roughness
SLA_BANJ_ROUGHNESS
Parameter: Shadow Intensity
SLA_BANJ_SHADOW_INTENSITY
Parameter: Clip
SLA_BANJ_CLIP
Parameter: Contrast
SLA_BANJ_CONTRAST